Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$151.90	7.203%	$162.8414	$162.84	$162.85	$162.80
Purchase #2	$69.51	12.790%	$78.4003	$78.40	$78.40	$78.40
Purchase #3	$191.56	5.441%	$201.9828	$201.98	$202.00	$202.00
Purchase #4	$99.26	6.180%	$105.3943	$105.39	$105.40	$105.40
Purchase #5	$192.97	10.807%	$213.8243	$213.82	$213.80	$213.80
Purchase #6	$92.77	10.846%	$102.8318	$102.83	$102.85	$102.80
Purchase #7	$135.91	11.276%	$151.2352	$151.24	$151.25	$151.20
7 purchase totals =	$933.88		$1,016.5101	$1,016.50	$1,016.55	$1,016.40